The advantage of the red wiggler is that they reproduce quickly, but they make castings slowly and are not as large and cannot take tropical heat. When the temperature is above 80 degrees, they start to die.The advantage of the African night crawler is that is is a larger worm, therefore it makes more castings in less time, but they don't reproduce as quickly as the red wiggler. They do make a higher quality casting.The reason African night crawlers make better castings is that they are larger worms, therefore the material they eat spends more time in the worm's gut before it is excreted, and that is where it picks up the nutrients to help your plants grow.Worms live 4-10 years in captivity, depending on the species.